package net_UDP;

import java.io.IOException;
import java.net.*;
import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: qian
 * Date: 2023-02-16
 * Time: 16:41
 */
public class UdpEchoClient {
    private DatagramSocket socket=null;

    private String serverIP;
    private int serverPort;
    public UdpEchoClient(String serverIP,int serverPort) throws SocketException {
        //客户端不指定端口，是因为不指定的话系统会给客户端分配一个空闲的端口
        socket=new DatagramSocket();
        this.serverIP=serverIP;
        this.serverPort=serverPort;
    }
     public void start() throws IOException {
         Scanner scanner=new Scanner(System.in);
        while(true){
            //1.从控制台读取用户输入的内容
            System.out.println("-> ");
            String request=scanner.next();
            //2.构造一个UDP请求，发送给服务器
            DatagramPacket requestPacket=new DatagramPacket(request.getBytes(),request.getBytes().length,
                    InetAddress.getByName(this.serverIP),this.serverPort);
            socket.send(requestPacket);
            //3.从服务器读取UDP响应数据，并解析
            DatagramPacket responsePacket=new DatagramPacket(new byte[4096],4096);
            socket.receive(responsePacket);
            String response=new String(responsePacket.getData(),0,responsePacket.getLength());
            //4.把服务台的响应显示到控制台上
            System.out.println(response);
        }
     }

    public static void main(String[] args) throws IOException {
        UdpEchoClient client=new UdpEchoClient("127.0.0.1",9090);
        client.start();
    }
}
